Lens driving mechanism

ABSTRACT

A lens driving mechanism is provided, including a bottom plate, a housing, a movable portion, and a biasing assembly. The housing is disposed on and connected to the bottom plate. The movable portion and the biasing assembly are disposed in the housing. The movable portion has a base and a holder, wherein the holder is configured to hold an optical lens and connects to the base. The biasing assembly connects the bottom plate and the movable portion, and is configured to force the movable portion to move relative to the bottom plate. When the holder moves to a limit position relative to the base, the holder contacts the housing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/421,576, filed on Nov. 14, 2016, and China Patent Application No.201710888582.5, filed on Sep. 27, 2017, the entirety of which isincorporated by reference herein.

BACKGROUND OF THE INVENTION Field of the Invention

The application relates in general to a lens driving mechanism, and inparticular to a lens driving mechanism that includes a housingconfigured to restrict the movement of the holder and the optical lensdisposed therein.

Description of the Related Art

Thanks to ongoing technological development, the most recent electronicdevices (such as tablet computers and smartphones) to be put on themarket are increasingly trending toward miniaturization, and theyusually include a lens module capable of aiding in photography orrecording video. The demands on these increasingly indispensableelectronic devices are also rapidly growing. However, an image may comeout blurry if the user shakes the lens module in the electronic device.To miniaturize the electronic device and improve image quality, it isincreasingly important to design a smaller and effectively shockprooflens module.

BRIEF SUMMARY OF INVENTION

To address the deficiencies of conventional products, an embodiment ofthe invention provides a lens driving mechanism configured to drive anoptical lens, including a bottom plate, a housing, a movable portion,and a biasing assembly. The housing is disposed on and connected to thebottom plate. The movable portion and the biasing assembly are disposedin the housing. The movable portion has a base and a holder, wherein theholder is configured to hold an optical lens and connect to the base.The biasing assembly connects the bottom plate and the movable portion,and is configured to force the movable portion to move relative to thebottom plate. When the holder moves to a limit position relative to thebase, the holder contacts the housing.

In some embodiments, the movable portion further includes a framedisposed on the base, and the frame does not overlap with the holder inthe direction of the optical axis of the optical lens.

In some embodiments, when the holder moves to the limit position, theholder protrudes from the frame.

In some embodiments, the movable portion further includes anelectromagnetic driving assembly disposed on the frame and the holderand configured to force the holder to move relative to the base.

In some embodiments, the electromagnetic driving assembly has at leastone magnetic element disposed on the frame, wherein the frame exposesthe magnetic element in the direction of the optical axis.

In some embodiments, the movable portion further includes a gluedisposed on an upper surface of the magnetic element, and the glueconnects the upper surface and the frame.

In some embodiments, the movable portion further includes a first leafspring connecting the holder and the frame, and the frame exposes thefirst leaf spring in the direction of the optical axis.

In some embodiments, the first leaf spring has an inner stringstructure, an outer string structure, and a bending structure, whereinthe inner string structure is connected to the holder, the outer stringstructure connects the base to the frame, the bending structure connectsthe inner and outer string structures, and the frame exposes the bendingstructure in the direction of the optical axis.

In some embodiments, the movable portion further includes a second leafspring connecting the holder and the base, and the holder is disposedbetween the first and second leaf springs.

In some embodiments, the biasing assembly includes a shape-memory alloy(SMA) material.

In some embodiments, the lens driving mechanism further comprises anelastic member disposed between the bottom plate and the movableportion, and the elastic member is connected to the biasing assembly.

In some embodiments, the elastic member has a flange structure extendingalong the direction of an optical axis of the optical lens, and theflange structure is closer to the optical axis than the holder is.

In some embodiments, the elastic member has an L-shaped arm and aprotruding portion, the arm connects the bottom plate, and theprotruding portion connects the movable portion.

In some embodiments, the bottom plate has a fixed portion, the elasticmember has a connecting portion, the fixed portion and the connectingportion is situated on the same side of the bottom plate, and thebiasing assembly connects the fixed portion and the connecting portion.

In some embodiments, the biasing assembly forces the movable portion tomove along an optical axis of the optical lens or forces the movableportion to rotate around the optical axis.

In some embodiments, the biasing assembly forces the movable portion tomove along a direction that is substantially perpendicular to the acentral axis of the bottom plate or forces the movable portion to rotatearound the central axis.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 is an exploded diagram of a lens driving mechanism according toan embodiment of the invention.

FIG. 2 is a schematic diagram of the lens driving mechanism in FIG. 1after assembly (the housing 20 is omitted).

FIG. 3 is a sectional view diagram of the movable portion 30 taken alongline B-B in FIG. 2.

FIG. 4 is a schematic diagram of the frame assembled with one magneticelement and the first leaf spring.

FIG. 5 is a schematic diagram of the first and second leaf springsconnecting the holder to the base.

FIG. 6 is a top plan view diagram of the lens driving mechanism in FIG.2 (the housing 20 is omitted).

FIG. 7A is a sectional view diagram of the lens driving mechanism inFIG. 1 after assembly taken along line A-A.

FIG. 7B is an enlarged view diagram of the area B in FIG. 7A.

FIG. 8 is a schematic diagram of connection of the bottom plate, theelastic member and the biasing assembly.

DETAILED DESCRIPTION OF INVENTION

The making and using of the embodiments of the lens driving mechanismsare discussed in detail below. It should be appreciated, however, thatthe embodiments provide many applicable inventive concepts that can beembodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the embodiments, and do not limit the scope of the disclosure.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which this invention belongs. It should be appreciated thateach term, which is defined in a commonly used dictionary, should beinterpreted as having a meaning conforming to the relative skills andthe background or the context of the present disclosure, and should notbe interpreted by an idealized or overly formal manner unless definedotherwise.

FIG. 1 is an exploded-view diagram of a lens driving mechanism 1according to an embodiment of the invention, and FIG. 2 is a schematicdiagram of the lens driving mechanism 1 after assembly (the housing 20is omitted). The lens driving mechanism 1 can be disposed in anelectronic device, such as a camera, a tablet computer, or a cell phone,and it can sustain an optical lens (not shown) and force (or drive) theoptical lens to move relative to an image sensor disposed in theelectronic device, so that the lens driving mechanism 1 has functions ofauto-focusing (AF) function and optical image stabilization (OIS), toenhance image quality.

As shown in FIGS. 1 and 2, the lens driving mechanism 1 primarilycomprises a bottom plate 10, a housing 20, a movable portion 30, abiasing assembly W, and an elastic member S. The housing 20 is connectedto and disposed on the bottom plate 10. The movable portion 30, thebiasing assembly W, and the elastic member S are disposed on the bottomplate 10 and situated in the housing 20 which is configured to protectthem. The movable portion 30 can sustain an optical lens, wherein animage sensor is configured to receive light from the outside of theelectronic device and through the optical lens so that an image may beacquired. The structure of the movable portion 30 is described in detailbelow, and the connection between the movable portion 30 and the bottomplate 10 will be described later.

Please refer to FIGS. 1 to 3, wherein FIG. 3 is a sectional view diagramof the movable portion 30 in FIG. 2. The movable portion 30 includes abase 31, a holder 32, a frame (inner frame) 33, an electromagneticdriving assembly ED, a first leaf spring 34, and a second leaf spring35. The holder 32 is configured to hold an optical lens and disposed onthe base 31, and the frame 33 is disposed on the holder 32. The firstand second leaf springs 34 and 35 connect the holder 32 to the base 31,and the holder 32 is sandwiched therebetween. The electromagneticdriving assembly ED includes a coil C and a plurality of magneticelements M (such as magnets) which are respectively disposed on theholder 32 and the frame 33. More specifically, the coil C is disposedaround the holder 32, and four magnetic elements M are connected to theframe 33 via the upper surfaces thereof and correspond to the coil C.

It should be noted that the connection of the magnetic elements M andthe frame 33 may be accomplished by applying a glue M1 (for example, atransparent glue). Specifically, as shown in FIG. 4, when the magneticelement M is provided on the frame 33, the frame 33 exposes at least aportion of the upper surface of the magnetic element M viewed from thedirection of the optical axis O of the optical lens. The glue M1 can beapplied directly to the upper surface of the magnetic element M fromabove, so that the magnetic element M is affixed (or connected;attached; adhered) to the frame 33. Therefore, since the frame 33exposes a portion of the magnetic element M, the glue M1 can be directlyapplied from above. Compared to a traditional connection mechanism whichthe magnetic element M is adhered by the inner sidewall of the frame 33or applying the glue M1 to the magnetic element M from below, thepresent embodiment has the effect of simplifying the assembly step andpreventing the glue M1 from flowing down along the sidewall of the frame33. In some embodiments, the glue M1 may fully cover the upper surfaceof the magnetic element M exposed by the frame 33 or partially appliedto the exposed upper surface of the magnetic element M. In addition, thefirst leaf spring 34 provided between the magnetic element M and theframe 33 may adhere to the frame 33 via glue M1 to simplify the assemblyprocess.

In the present embodiment, the coil C may receive one or more drivingsignals (such as electrical current) supplied by an external powersource (not shown), so that a magnetic force or forces can be providedbetween the coil C and the magnetic elements M so that theelectromagnetic driving assembly ED can force (or drive) the holder 32and the optical lens disposed therein to move together with respect tothe base 31 along the optical axis O (Z-axis) to achieve auto-focusing,or when the optical lens is shaken, the aforementioned movementcompensates, in order to achieve the purpose of an anti-shake function.Furthermore, before applying the driving signal, the holder 32 can bepositioned in an initial position with respect to the base 31 by thefirst and second leaf springs 34 and 35.

FIG. 5 is a schematic diagram of the holder 32 connecting to the base 31via the first and second leaf springs 34 and 35. The base 31 has fourprotrusions 312 (such as protruding columns) respectively disposed onfour corners of the main body 311 of the base 31. The first and secondleaf springs 34 and 35 connect the protrusions 312 and the holder 32, sothat the holder 32 is movably connected to the base 31. It should benoted that the first leaf spring 34 has an inner string structure 341,an outer string structure 342, and a bending structure 343. The innerstring structure 341 has a substantially circular structure (shape) andis disposed on the holder 32, and the outer string structure 342 has asubstantially rectangular structure (shape) and is disposed on theprotrusions 312. The bending structure 343 connects the inner and outerstring structures 341 and 342.

It should be noted that the frame 33 exposes the holder 32 and thebending structure 343 of the first leaf spring 34 (the bending structure343 is exposed) when viewed from the direction of the optical axis O, asshown in FIG. 6. Moreover, the frame 33 does not overlap with the holder32 in the direction of the optical axis O. When the electromagneticdriving assembly ED forces the holder 32 and the optical lens to moveupward relative to the base 31 and the frame 33 along the optical axisO, the holder 32 can move to a position that is higher than the uppersurface of the frame 33 (the holder 32 protrudes from the upper surfaceof the frame 33), and the holder is restricted (limited) by the housingat a limit position X1 (please refer to FIGS. 7A-7B, the holder 32 isrestricted due to it being in contact with (touching) the housing 20when moving upward). In this way, compared to a transitionalposition-limiting mechanism/stopping mechanism in which the holder islimited by the inner frame, in the present embodiment, instead of theframe 33 serving as a stopping mechanism (the holder 32 does not touchor contact the frame 33), the housing 20 is configured to limit theholder 32. Therefore, the distance of movement of the holder 32 in thehousing 20 (in the direction of the optical axis O) is effectivelyincreased so that the auto-focusing and optical image stabilization ofthe optical driving mechanism 1 are improved, and it is possible toreduce the thickness of frame 33 in the direction of the optical axis O(due to it no longer serving as the stopping mechanism), therebyachieving the purpose of miniaturization.

Next, the connection of the movable portion 30 to the bottom plate 10 isdescribed in detail below.

Please refer to FIGS. 1, 2 and 8, in which the bottom plate 10 has acentral axis Q, wherein the optical axis O coincides with the centralaxis Q when the optical lens (disposed in the movable portion 30) is inthe initial position. The bottom plate 10, which may be a flexibleprinted circuit board (FPCB), is disposed under the base 31 of themovable portion 30, and the elastic member S and the biasing assembly Ware disposed between the bottom plate 10 and the base 31 (of the movableportion 30). The bottom plate 10 and the base 31 are connected to eachother by the biasing assembly W and the elastic member S.

More specifically, still referring to FIGS. 2 and 8, the biasingassembly W has four elongated biasing wires that correspond to the foursides of the bottom plate 10 (with a substantially rectangularstructure). The two ends of each biasing wire are respectively connectedto the fixed portion 11 of the bottom plate 10 and the connectingportion S1 of the elastic member S, wherein the fixed portion 11 and theconnecting portion S1 extend along the direction of optical axis O(Z-axis) and extend toward the base 31. The elastic member S is disposedbetween the bottom plate 10 and the base 31 and connects them.

The biasing assembly W, including a plurality of biasing wires made of ashape-memory alloy (SMA) material, is also connected to the bottom plate10 and the movable portion 30. The lengths of the biasing wires can bechanged by applying driving signals (e.g., electrical current) to thebiasing wires from an external power source (not shown). For example,when applying one or more driving signals to heat the biasing assemblyW, the biasing assembly W is able to deform (e.g., become elongated orshortened). When the application of the driving signals is stopped, thedeformed biasing assembly W will recover to its original length. Inother words, by applying one or more appropriate driving signals, thelength of the biasing assembly W can be controlled to move the movableportion 30 (including the holder 32 and the optical lens) relative tothe bottom plate 10, to alter the posture (position) of the movableportion 30. Thus, the lens driving mechanism 1 has the function ofoptical-shaking compensation and optical-image stabilization.

The biasing assembly W, for example, may include a titanium-nickel(TiNi) alloy, a titanium-palladium (TiPd) alloy, atitanium-nickel-copper (TiNiCu) alloy, a titanium-nickel-palladium(TiNiPd) alloy, or a combination thereof.

Still referring to FIGS. 2 and 8, the elastic member S (such as a sheetspring) has a metal material and a substantially rectangular structure,and includes two arms S2 and two protruding portions S3 which arerespectively connected to (or which contact) the movable portion 30 andthe bottom plate 10. The elastic member S (the arms S2 and theprotruding portions S3 thereof) may be connected to conductive wires(not shown) which are formed on the bottom plate 10 and the base 31 ofthe movable portion 30 by insert molding or 3D molded interconnectdevice (MID) technology. Thus, those conductive wires are connected tothe four biasing wires via the elastic member S to form four respectiveindependent circuits, whereby driving signals (e.g., current) can besupplied to those biasing wires (the biasing assembly W) respectivelyfrom an external power source via the conductive wires, and the lengthof each of the biasing wires can be changed so that the movable portion30 can move relative to the bottom plate 10.

It should be noted that, due to the conductive wires formed on the base10 and the bottom 20 by insert molding or 3D molded interconnect devicetechnology, the number of components of the lens driving mechanism 1 canbe reduced and the dimensions thereof can be greatly decreased.

As shown in FIG. 8, the four biasing wires of the biasing assembly W arerespectively disposed on the four sides of the bottom plate 10 andcorresponding to the four sides of the lower surface of the base (FIG.2). Each side of the bottom plate 10 is provided with one fixed portion11 and one connecting portion S1 which are connected via the biasingwire. Specifically, the two fixed portions 11 and the two connectingportions S1 are respectively disposed at the four corners of the bottomplate 10 and positioned in a staggered configuration (that is, any twoadjacent corners are provided with one connecting portion S1 and onefixed portion 11). Furthermore, the substantially rectangular bottomplate 10 defines a diagonal line N, and the four biasing wires and theconnecting portions S1 are substantially symmetrical to the diagonalline N.

In addition, the opening of the elastic member S is formed with acircular-shaped (or substantially circular-shaped) flange structure S4,extending along the central axis Q/optical axis O and toward the holder32. As shown in FIGS. 6 and 7A, the flange structure S4 is received inthe holder 32 and overlaps with the holder 32 (the flange structure S4and the holder 32 are overlapping) in a direction that is perpendicularto the optical axis O, and is closer to the central axis Q/optical axisO than the holder 32. By forming the flange structure S4, it is possibleto avoid or reduce the amount of external dust or particles that canenter the holder 32 and impair the optical lens, thereby greatlyimproving the product.

Referring to FIGS. 2 and 8, when applying the appropriate drivingsignals to the biasing assembly W, the biasing assembly W deforms (e.g.,by being shortened or elongated) so that the movable portion 30 (and theoptical lens disposed therein) are moved relative to the bottom plate10, to achieve optical image stabilization.

Two types of motion of the movable portion 30 relative to the bottomplate 10 may be applied: the movable portion 30 may move linearlyrelative to the bottom plate 10 in a direction that is substantiallyperpendicular to the central axis Q (XY-plane), or the movable portion30 may rotate around the central axis Q. Thus, the positional andangular compensation for the movable portion 30 can be accomplished bycontrolling the deformation of the biasing assembly W which receives theappropriate drive signal. In addition, since the movable portion 30 andthe bottom plate 10 are also connected through the elastic member S,when the drive signals have not yet been applied to the biasing assemblyW, the movable portion 30 can be positioned by the elastic member S inan initial position with respect to the bottom plate 10.

With respect to the movement of the movable portion 30 relative to thebottom plate 10, for example, as shown in FIG. 8, when appropriate drivesignals are applied to the two biasing wires which are opposite eachother in FIG. 8, causing them to elongate and contract, respectively(the elongated biasing wire elongates toward the connecting portion 11;the contracted biasing wire contracts toward the fixed portion 11), thebiasing assembly W forces the movable portion 30 to move linearly in adirection that is perpendicular to the central axis Q with respect tothe bottom plate 10. Similarly, when applying appropriate drive signalsto these two biasing wires, causing both them to contract, the biasingassembly W forces the movable portion 30 to rotate around the centralaxis Q relative to the bottom plate 10.

Alternatively, in some embodiments, the biasing assembly W may includeone biasing wire disposed on a side of the bottom plate 10, and aguiding mechanism (such as a guiding rail, not shown) is correspondinglyprovided for guiding the movable portion 30, to force the movableportion 30 to move linearly or rotate relative to the bottom plate 10.

In summary, a lens driving mechanism is provided, configured to drive anoptical lens, primarily including a bottom plate, a housing, a movableportion, and a biasing assembly. The housing is disposed on andconnected to the bottom plate. The movable portion and the biasingassembly are disposed in the housing. The movable portion has a base anda holder, wherein the holder is configured to hold an optical lens andis connected to the base. The biasing assembly connects the bottom plateto the movable portion, and is configured to force the movable portionto move relative to the bottom plate. When the holder moves to a limitposition relative to the base, the holder contacts the housing. In thisway, the optical driving mechanism has a better focusing function andbetter optical shaking compensation due to a larger space being providedfor the holder to move, thereby improving image quality. Furthermore,because the holder is restricted by the housing, the overall size of thelens driving mechanism can be reduced because there are fewerrestriction/stopping mechanisms for the holder.

Use of ordinal terms such as “first”, “second”, “third”, etc., in theclaims to modify a claim element does not by itself connote anypriority, precedence, or order of one claim element over another or thetemporal order in which acts of a method are performed, but are usedmerely as labels to distinguish one claim element having a certain namefrom another element having the same name (but for use of the ordinalterm) to distinguish the claim elements.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the invention. It isintended that the standard and examples be considered as exemplary only,with the true scope of the disclosed embodiments being indicated by thefollowing claims and their equivalents.

What is claimed is:
 1. A lens driving mechanism, configured to drive anoptical lens, comprising: a bottom plate; a housing, connected to anddisposed on the bottom plate; a movable portion, disposed in thehousing, including: a base; and a holder, configured to sustain theoptical lens and movably connected to the base; and a biasing assembly,disposed in the housing and connecting the bottom plate and the movableportion, configured to force the holder and the base of the movableportion to move relative to the bottom plate; wherein when the holdermoves to a limit position relative to the base, the holder is in contactwith the housing.
 2. The lens driving mechanism as claimed in claim 1,wherein the movable portion further includes a frame disposed on thebase, and the frame does not overlap with the holder in the direction ofan optical axis of the optical lens.
 3. The lens driving mechanism asclaimed in claim 2, wherein when the holder moves to the limit position,the holder protrudes from the frame.
 4. The lens driving mechanism asclaimed in claim 2, wherein the movable portion further includes anelectromagnetic driving assembly disposed on the frame and the holderand configured to force the holder to move relative to the base.
 5. Thelens driving mechanism as claimed in claim 4, wherein theelectromagnetic driving assembly has at least one magnetic elementdisposed on the frame, wherein the frame exposes the magnetic element inthe direction of the optical axis.
 6. The lens driving mechanism asclaimed in claim 5, wherein the movable portion further includes a gluedisposed on an upper surface of the magnetic element, and the glueconnects the upper surface and the frame.
 7. The lens driving mechanismas claimed in claim 2, wherein the movable portion further includes afirst leaf spring connecting the holder and the frame, and the frameexposes the first leaf spring in the direction of the optical axis. 8.The lens driving mechanism as claimed in claim 7, wherein the first leafspring has an inner string structure, an outer string structure, and abending structure, wherein the inner string structure is connected tothe holder, the outer string structure connects the base and the frame,the bending structure connects the inner and outer string structures,and the frame exposes the bending structure in the direction of theoptical axis.
 9. The lens driving mechanism as claimed in claim 7,wherein the movable portion further includes a second leaf springconnecting the holder and the base, and the holder is disposed betweenthe first and second leaf springs.
 10. The lens driving mechanism asclaimed in claim 1, wherein the biasing assembly includes a shape-memoryalloy (SMA) material.
 11. The lens driving mechanism as claimed in claim1, further comprising an elastic member disposed between the bottomplate and the movable portion, and the elastic member is connected tothe biasing assembly.
 12. The lens driving mechanism as claimed in claim11, wherein the elastic member has a flange structure extending alongthe direction of an optical axis of the optical lens, and the flangestructure is closer to the optical axis than the holder is.
 13. The lensdriving mechanism as claimed in claim 11, wherein the elastic member hasan L-shaped arm and a protruding portion, the arm is connected to thebottom plate, and the protruding portion is connected to the movableportion.
 14. The lens driving mechanism as claimed in claim 11, whereinthe bottom plate has a fixed portion, the elastic member has aconnecting portion, the fixed portion and the connecting portion issituated on the same side of the bottom plate, and the biasing assemblyconnects the fixed portion and the connecting portion.
 15. The lensdriving mechanism as claimed in claim 11, wherein the biasing assemblyhas a plurality of biasing wires respectively disposed on sides of thebottom plate, and the biasing wires connect the bottom plate and theelastic member.
 16. The lens driving mechanism as claimed in claim 1,wherein the biasing assembly forces the movable portion to move along adirection that is substantially perpendicular to the a central axis ofthe bottom plate or forces the movable portion to rotate around thecentral axis.